Refrigerating apparatus



Nam 29, 1938. c. A. MANNY REFRIGERATING APPARATUS Filed Oct. 24, 1934 2 Sheets-Sheet 1 I INVENTOR. (z-c: 14 14. /74/m ATTORNEY,

Filed Oct. 24, 1934 2 Sheets-Shem: 2

INVENTOR. 656 A i 5 5420 ATTORNL" Patented Nov. 29, 1938 2,138,660

REFRIGEBATING APPARATUS Cecil A. Mann, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a. corporation of Delaware Application October 24, 1934, Serial No. 749,787

9 Claims. (Cl. 173-311) This invention relates to refrigerating apparatus, particularly of the compressor-condenserexpander type and specifically concerns the problem of satisfactorily providing current conpanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a diagrammatic viewof a refrigerating apparatus embodying the present invention, a

ducting lead-ins for a hermetically sealed motorcompressor unit for use in refrigerating apportion of the compressor thereof being broken paratus. away and shown partially in section;

In refrigerating apparatus and other devices Fig. 2 is a view showing the parts of the lead-in employing a motor-compressor unit in which construction in disassembled relation before both the motor and compressor are enclosed by fusing; 10 a hermetically sealed casing of metal, it'is neces- Fig. 3 is a cross section of a conductor lead-in sary to provide some form of lead-in for carrying bushing at a preliminary stage of assembly; current to the motor through the wall of the Fig. 41s a view corresponding to Fig. 3 showing hermetically sealed housing which not only inthe construction of the bushing at a later stage sures perfect insulation of the conductor from of manufacture; 15 the housing,.but also maintains a hermetic seal. Fig. 5 is a sectional view of a portion of the Heretofore, in providing lead-ins for compressors motor-compressor unit showing the lead-in bushof the present type, it has been customary either ing at a still later stage of manufacture; to provide a resilient insulating material which Fig. 6 is a cross section of a portion of a motor- 0 is clamped in place after the manner of a stufling compressor unit showing a finished lead-in bushbox or to utilize a vitreous insulating material ing; and such as glass which is packed in position around Fig. 'l is a view corresponding to Fig. 5, but the conductor wire while heated to a plastic conshowing an optional method of constructing the dition. It has'been found after testing numerbushing. I ous motor-compressor units having lead-ins of Referring now to Fig. 1, there is shown arethe aforementioned types that slight variations frigerating apparatus comprising a hermetically 25 occurring in quantity production cause a consealed motor-compressor unit in which includes siderable percentage of such units to leak at the a motor I2, a compressor l4 and a sealed housing lead-in. It will be readily seen that in a motorcomprising a dome portion I6 and a base portion compressor unit for a refrigerating apparatus, 1 18 which may be assembled together and suitably 30 any leak, no matter how minute, will result in sealed to each other as by welding. The comeventually reducing the charge of refrigerant in .pressor I4 delivers compressed refrigerant the apparatus to a. point where it will no longer through a conduit 20 to a condenser 22 where operate efficiently, if at all, and inasmuch as the the refrigerant is liquefied and delivered by sole reason for utilizing a hermetically sealed means of conduit 24 to a heat interchanger 26, 35 motor-compressor unit inarefrigerating apparawhence the cooled liquid refrigerant passes by tus is to prevent the possibility of leakage and the conduit 28 to a refrigerant flow control deconsequent loss of the refrigerant charge, it bevice 30 which may comprise a fixed restrictor comes extremely important to eliminate all p05- in the form of a passage of small cross section but sibilities for leakage. great length. The expanding refrigerant leav- 40 It is an object of the present invention, thereing the restrictor 30 enters the evaporator 32 fore, to provide a novel motor-compressor unit where it vaporizes, withdrawing heat from an having a 1ead-in conductor which is imperviously object to be cooled (not shown). The vaporized sealed to a wall of the housing of a. motor-co refrigerant is returned to the compressor through pressor unit, as well as electrically insulated a Conduit 34 recompression- 45 therefrom. I In order to provide for delivering current to A further object is to provide a novel manner the windings of the motor from a source of assembling portions of a motor-compressor side h *F the lead'm Pondllcms unit of a hermetically sealed type for providing ig ggg ig gg g igg ig $3fi% g}: 333

3 53255? seal msulatwn at the t nected to the lead-in conductors 36, while the A further object to provide a motor com outer ends of the conductors 36 are suitably connected to the. usual supply line through the pressor unit having hermetically sealed and elecnecessary control switches In their finished tncany insulated leadm condugtors Yvhlch m form (see Fig. 6) the lead-in conductors 36 com- 55 be produced at low cost and to provide a novel prise a metallic cylindrical bushing 38 having method for constructing the Same an outwardly turned flange 40 at the top and an Further objects and advantages of the present inwardly t d flange 42 t th b tt m Th inv n i n w e apparent fr m the following bushing 38 is filled with a body of vitreous insulating material 44 which surrounds the condescription, reference being had to the accomgeueous and without voids.

ductcr wire 56 which in turn is centrally located within the bushing The bottom portion the bushing is filled with a of a refractory material which ose later to be described. ording to the present inventio lead-in cond ted in accor 1; materi fli. bushing to l ursh pro;

our

perm of refracto serteo. nt. packed 1. The pe et e c" any suitable r actory inatcri 1 ha g the properties or" refra tor body which w ll i treng rout sagrequired For eample, clays are suitable, mixed with about an equal The purpose of the refractory p ging c recus boog known fire to lose the vitmany or the well particularly when ntity of feldspar. ellet merely to hold the conducting wire 56; in proper location during the construction of the lead-in and to prevent the fused vitreous body from running out the bottom of the bushing when in a molten condition. At the time the pellet eh: is first cs sembled into the bushing is in somewhat plastic condition suficient to permit it to be readily packed or taniped into the bottom of the bushing bG effectively seal the same during the subsequent steps production of-the lead-in and to pal: tightiy around the conductor wire to maintain its location properly. A lead ln bushing assembled to the point thus described is illustrated in Fig. 3.

The bushing is next filled to substantially the top with a vitreous frit. The frit used is essentiall 1 tie same as any of the various irits used in the porcelain enameling art for coating metal articles and it is preferred to utilize a frlt of the ground coat type. The body of frit thus inserted may be either in a loose form and mixed with sufficient water to make it a somewhat plastic mass, or may be in the form or" a gore-formed pellet such as pellet 58 in Fig. 2. a second preformed pelle 52. is then slipped over the conductor 45 to rest on the previously inserted body of frit and to extend above the top of the bushing so as to provide suidcient material tcsubstanti'ally till the bushing after the frit has boiled down in thefiring operation. The bushing assembled to the stage thus far described is then placed in a furmace and heated to the proper temperature for a sufiicient length of time to fuse the hit in the bushing 38. It preferrecl to continue the firing operation suiiiciently long to permit the frit to boil down to the stage where gas bubbles are no longer formed in order to insure that the body of vitreous material in the lead-in will be homo- The length of time necessary will vary according to the composition of the frlt and the temperature of firing, but in general, should be from one to four hours. The condition of the lead-in after this operation is illustrated in Fig. 4 wherein there is shown the fused body of vitreous material 56, substantially filling the bushing 38 above the pellet 48.

.e bushing is next assembled a erture in. the base member it an tity of spelter material is ap lied the l in 38 and the aperture lhot'. er pro-formed pell.t 5: e frit is then located. on top the assembly again f' ecl in a a e. Thesecond firing o .eration r and remelts the body of vit- "1- causing the two to unite into the s r-ody of vitreous material M, which, d. ed mater provided by the pellet s the top of t :8 bushing and seals e tothe base member Hi Whicl. as shown Z1119: h a suitable depression adjacent the The spelter material is also melted second firing operation which causes re e to be made at the joint between. the ashis plate l8.

:1 to conduct the second ii .1 at the same time that other portions of compressor mechanism such as the filling the bottom plate and the shaft and the inlet connection. 56 are brazed to the plate ill. Th se operations are preferably conducted ina furnace having a reducing atmosphere in order to secure conveniently a satisfactory brazed joint. In this preferred. practice of the invention, a vitreous frit is selected for the l as lead-in bushing which has satisfactory fusing characteristics a reducing atmosphere. Such a frit should have minimum percentages of oxides which upon reduction at the surface of the molten irit body form a layer of a conducting metal. Likewise, it is preferred to use a hit which has a minimum tendency to boil in a reducing atmosphere such as is displayed by many frits having large L ercentages of readily reducible oxides.

The lead-in conductor which is formed by the method-heretofore described presents several ad.- vantages over lead-ins heretofore constructed. In addition to being capable of manufacture at relatively low cost, the present method produces a lead-in which not only has permanent electrical insulating qualities of a high character due to the vitreous nature of the insulating body 44 but also provides a hermetic seal which like 'ise is permanent and in which the occurrence of minute leaks due to variations arising in production in large quantities is minimized. The seal provided between the body of vitreous material 44 and both the conductor 46 and the bushing 38 is far-superior to that obtained by any previous method; While the exact nature of the junction between the metal and the vitreous body is not known at present, it has been found upon breaking apart a large number of lead-ins constructed in this manner that the adhesion'of the vitreous body to the metal is greater than the cohesion of the vitreous body itself. It will be understood. of course, that various other forms of lead-ins may be constructed and that the method of construction may be modified. For example, the method may be followed such as that illustrated in Fig. 7 in which the bushing 38, the refractory pellet 48 and all of the vitreous frit required are assembled together, and, without pro-firing, the bushing and assembled parts are inserted in the aperture in the base plate with the application of a suitable spelter. The vitreous material is fired in one operation which preferably takes place at the same time the brazing of the other compressor parts to the base 88 is performed. Fig. '7 also illustrates the use of but a single pro-formed pellet 60 of vitreous frit which serves to provide sufficient frit to substantially fill the bushing 38 and to overfiow the top thereof.

In some applications of the present invention, depending somewhat on the nature of the refractory material used for the pellet 48 and upon the subsequent treatment of the base plate assembly after the final firing operation, it may be desirable to remove the refractory pellet 48. For example, if a refractory material is used for the pellet 48, which does not glaze on the outer surface during firing and if the base plate assembly is subjected to pickling, plating or other treatments after firing, which will cause the refractory pellet to absorb acids, the lower portion of the bushing 38 may be turned off with a suitable tool and the refractory pellet removed to expose the lower surface of the vitreousbody 44 which is, of course, glass hard and impervious to moisture or acids.

While the form of embodiment of the invention as herein described, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. The method of forming a fluid tight insulated lead-in for a sealed motor-compressor unit which comprises forming an aperture in a wall of the unit, placing in the aperture a pre-fired assembly comprising a metal bushing and a conductor secured therein by a body of vitreous insulation, placing a body of vitreous frit around the conductor above the body of vitreous insulation, applying spelter material adjacent the bushing in the aperture, and simultaneously firing the entire assembly at a temperature to both braze the metal bushing to the wall of the unit and to melt the frit.

2. The method of forming a fluid tight insulated lead-in for a sealed motor-compressor unit which comprises forming an aperture in a wall of the unit, placing in the aperture a pre-fired assembly comprising a metal bushing and a conductor secured therein by a body of vitreous insulation, placing a body of vitreous frit around the conductor above the body of vitreous insulation, applying spelter material adjacent the bushing in the aperture, and simultaneously firing the entire assembly at a temperature to both braze the metal bushing to the wall of the unit and to melt the entire body of vitreous material associated with said sleeve and conductor.

3. The method of forming a base for a sealed motor-compressor unit having an apertured metallic housing member which comprises assembling a metal bushing, a conductor and a body of vitreous frit in said aperture, applying spelter to portions of the metal parts and firing the entire assembly at a temperature to both braze metal parts together and melt the vitreous frit.

4. The method of forming a base for a sealed motor-compressor unit having an apertured metallic housing member which comprises assembling a metal bushing, a conductor and a body of vitreous frit in said aperture, applying spelter to portions of the metal parts and firing the entire assembly at a temperature to both braze metal parts together and melt the vitreous frlt, and in a reducing atmosphere.

5. The method of forming a base for a sealed motor-compressor unit which comprises assem bling a plurality of metal compressor parts including an apertured housing member, assembling a'metal bushing, a conductor and a body of vitreous frit in said aperture, applying spelter to portions of the metal parts and firing the entire assembly at a temperature to both braze the metal parts together and melt the vitreous frit, and in a reducing atmosphere, the inner surface of said bushing and the outer surface of said conductor being formed of enamelling iron, and said vitreous material comprising a porcelain enamel.

6. The method of forming a base for a sealed motor-compressor unit which comprises assembling a plurality of metal compressor parts, forming a metallic walled aperture in the base, supporting a conductor in said aperture but out of contact therewith by a structure sealing one end of said aperture and made of material which does not become molten at the firing temperature used, filling the space between the conductor and the aperture walls with a vitreous frit which becomes molten at the firing temperature used, applying spelter to portions of the metal parts and firing the entire assembly at a temperature to both braze the metal parts together and melt the vitreous frit.

7. The method of forming a fluid-tight insulated lead-in for a sealed motor-compressor unit which comprises forming a cup-shaped metallic bushing member with an aperture at its bottom, placing a perforated pellet of a refractory material in the bottom of said bushing for closing said aperture and for supporting a conductor in said aperture out of contact with the walls of said aperture during firing, which refractory material does not become molten at the firing temperature used, placing a vitreous frit in said cup-shaped bushing, firing the assembly at a temperature to melt the frit, cooling the assembly, and then removing the pellet of refractory material.

8. The method of forming a fluid-tight insulated lead-in which comprises forming a metal bushing member with an aperture at its bottom, placing a perforated pellet of refractory material inthe bottom of said bushing for closing said aperture and for supporting a conductor in said aperture but out of contact with the walls of said aperture, which refractory material does not become molten at the firing temperature used, placing a vitreous frlt between said conductor and the walls of said bushing, which frit being substantially free of readily reducible oxides, firing the assembly in a reducing atmosphere at a temperature to melt the frit, cooling the assembly, and then removing the pellet of refractory material.

9. The method of forming a casing for a sealed motor compressor which comprises nesting one or more metal compressor parts with portions of a metal casing part, nesting a lead-in with a portion of said metal casing part, said lead-in having an outer metal bushing and an insulated conductor supported therein by means of a pellet of refractory material, which refractory material does not become molten at normal firing temperatures, placing spelter material to the joints between the metallic parts, placing a vitreous frit substantial- 1y free of readily reducible oxides between said oute'r metal bushing and said insulated conductor therein, and firing the assembly in a reducing atmosphere to a temperature to melt the frit and the spelter material. I

- CECIL A. MANN. 

